1. Field of the Invention
This invention relates to article transport systems, and more particularly to an article transport system including a plurality of stations for loading and unloading articles, a carriage for transporting articles between the stations, and a control device installed on the ground to control running of the carriage.
2. Description of the Related Art
In a conventional article transport system of the type noted above, the plurality of stations and the control device on the ground are interconnected through wires. Article transport requests are made from the stations through the wires.
The stations and carriage have optical communication units, respectively, to communicate with each other. When the carriage stands still at one of the stations, the control device on the ground transmits running instructions to the carriage through the optical communication units of the station and carriage and the wire extending between this station and control device.
In an article transport system including a home position for the carriage to stand by, the home position is wired to the control device on the ground, and the home position and carriage both have optical communication units to communicate with each other. When the carriage stands still in the home position, the control device on the ground transmits running instructions to the carriage through the wire and optical communication units.
Where the stations are used for transport of varied articles to and from assembly lines, for example, alterations to the assembly lines may require additional stations to be installed or existing stations to be relocated.
In the conventional systems, the wiring or piping must be provided between each station and the control device on the ground. This makes addition or relocation of the stations difficult. The conventional systems have room for improvement in this respect.